On electron-hole symmetry and phase separation in some electron doped cuprates

Analyzing the experimental NMR data for electron-doped cuprates, we concluded that the Coulomb effects caused by doping lead to dynamical spatial phase separation that contributes to the nuclear spin relaxation. Remarkable, the ``infinite-layer'' Sr$_{0.9}$La$_{0.1}$CuO$_{4}$ reveals unexpected electron-hole symmetry. Its $^{63}$Cu nuclear spin relaxation rate is the sum of a constant and the temperature dependent components, moreover, the latter turns out to be identical to the $1/63T_{1}(T)$-behavior in the stoichiometric YBa$_{2}$Cu$_{4}$O$_{8}$. Connection to fluctuation of a magnetic sub-phase is discussed.